© 2011 the mcgraw-hill companies, inc. chapter 2 psychology’s scientific method
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© 2011 The McGraw-Hill Companies, Inc.
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Psychology’s Scientific Method Types of Psychological Research Research Samples and Settings Analyzing and Interpreting Data Conducting Ethical Research Thinking Critically About Research Scientific Method and Health and Wellness
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Scientific Method
Science is a method.
It’s not what you study,
but how you study it.
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Scientific Method
1. observe some phenomenon
2. formulate hypothesis and predictions
3. test through empirical research
4. draw conclusions
5. evaluate the theory
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Scientific Method: Observe
Step 1
Observe some phenomenon
curiosity
variables
theory
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Scientific Method: Hypothesize
Step 2
Formulate hypotheses and predictions
testable prediction
derived from theory
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Scientific Method: Research
Step 3
Test through empirical research
operational definition of variables
analyze data using statistical procedures
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Scientific Method: Conclusions
Step 4
Draw conclusions
replication of results → reliability
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Scientific Method: Evaluate
Step 5
Evaluate the theory
change the theory?
peer review and publication
meta-analysis
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Descriptive Research
Goal: Describing a phenomenon
observation surveys and interviews case studies
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Descriptive Research
Descriptive research does
not answer questions about
how and why things are the
way they are.
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Correlational Research
Goal: Identify relationships
correlation coefficient: r
-1.00 ≤ r ≤ 1.00
strength of relationship: magnitude
direction of relationship: + / -
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Correlational Research
Positive Correlations factors vary in same direction ↑ and ↑ … or … ↓ and ↓
Negative Correlations factors vary in opposite direction ↑ and ↓ … or … ↑ and ↓
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Correlation and Causation
correlation does not equal causation
third variable problem
longitudinal design
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Experimental Research
Goal: Determine causation
random assignment
independent variable(s) – manipulation
dependent variable(s) – measurement
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Experimental Research
Experimental Group independent variable is manipulated
Control Group treated equally, except no
manipulation of independent variable
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Validity
External Validity representative of real world issues? do results generalize to the real world?
Internal Validity are dependent variable changes the result of
independent variable manipulation? bias? logical errors?
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Bias and Expectations
experimenter bias
demand characteristics
research participant bias
placebo effect
double-blind experiment
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Example of Experimental Research – Self Esteem
Baumeister’s research findings:
“high self esteem leads to aggression”
Donnellan & Trzesniewski’s research findings: “low self esteem leads to aggression”
What accounts for these different findings? lab-only aggression? type of self esteem?
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Applying Different Research Methods to Same Phenomenon
Example: Election of President Barack Obama
Possible Research Methods
observation
survey and interview
case studies
correlational research
experimental research
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Research Sample
Population entire group about whom conclusion drawn
Sample portion of population actually observed
Representative Sample characteristics similar to population opposite of “biased sample”
Random Sample equal chance of being selected
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Research Settings
“Artificial” world – laboratory setting controlled setting
Real world - natural setting naturalistic observation
What are the advantages and disadvantages
of each setting?
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Analyzing and Interpreting Data
Statistics mathematical methods used to report data
Descriptive Statistics describe and summarize data
Inferential Statistics draw conclusions about data
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Descriptive Statistics
Measures of Central Tendency mean median mode
Measures of Dispersion range standard deviation
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Inferential Statistics
does data confirm the hypothesis?
statistical significance
α = 0.05 (confidence level)
bridge between sample and population
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Research Ethics
research participants have rights Institutional Review Board (IRB) APA Guidelines
informed consent
confidentiality
debriefing
deception
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Animal Research in Psychology
animal research has benefited humans used by 5% of researchers rats and mice used 90% of time standards of care in animal research
housing
feeding
psychological and physical well being
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Reality TV – Ethical Issues
informed consent?
deception?
psychological and/or physical risk?
is the behavior real?
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A Wise Consumer…is skeptical yet open-minded!
Cautions exercise caution in applying group trends to
individual experience avoid overgeneralizing results look for converging evidence question causal inferences consider the source
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Expressive Writing & Health
Results of study on suicide v. accidental death different survivor health different survivor rate of talking about the loss
Results lead to study on writing those assigned to write about a trauma
experienced better physical health
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Chapter Summary
Explain what makes psychology a science. Discuss common research settings and the main
types of research that are used in psychology. Distinguish between descriptive statistics and
inferential statistics. Discuss some challenges that involve ethics, bias,
and information. Discuss scientific studies on the effect of writing
about ones trauma.
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Chapter Summary
Steps of the Scientific Method observe, hypothesize, research,
conclude, evaluate
Research Methods and Settings descriptive, correlational, and
experimental studies conducted in natural settings or the lab